5
Niels Bohr Nobel Prize – 1922 “For his services in the investigation of the structure of atoms and the radiation emanating from them” Five facts from the next four slides…

6
Niels Bohr’s Atom (Slide 1 of 3) Electrons move around the nucleus in orbits, like a solar system. The orbits are sometimes called energy levels. Planetary Model Electrons cannot exist between orbits (energy is quantized)

7
(Slide 1b of 3) Electrons cannot exist between orbits – think of rungs on a ladder. You can’t be in between one rung and another.

8
Bohr’s Atom (Slide 2 of 3) Electrons closest to the nucleus are lowest in energy. Electrons farthest from the nucleus are highest in energy. Ground state- electrons are in the lowest energy level possible Excited state - If energy is put into the atom, the electrons will jump up in energy (move away from the nucleus)

9
Bohr’s Atom (Slide 3 of 3) Excited electrons naturally go back to ground state. In order to do this, energy must leave the atom. Because energy is quantized in an atom, the amount of energy that leaves is the difference in energy between orbits. If this energy is in the visible light range, we will see certain colors

10
Atomic Spectra Absorption: When energy is added and an electron moves from a lower energy level to a higher energy level Emission: When an electron falls from a higher energy level to a lower energy level and a photon is emitted. The energy of each absorbed or emitted photon corresponds to a particular frequency, E = hν